I am running a 26/38 Shimano with a 11-36 rear and a long cage Shadow plus rear derailleur. I have no issues. The Shadow Plus clutch mechanism pretty much eliminates chain slap.

SRAM doesn't list the max capacity for their rear derailleurs, so you may have to e-mail them and ask them if it will work. If the rear derailleur has a clutch mechanism, you will likely e fine going with a long cage.

I remember seeing a few threads that discuss SRAM derailleur capacity (which is different from the max tooth size).

I have recently set up a short cage on a 2X10 39/26 and 11-36 on my ASR 5. I know its not ideal, but I got a great deal on a short XO type 2 and thought what the hell. My preliminary tests show that it is definitely too short to take up all the slack in 26x11 while still letting me comfortably hit 39x36. Obviously. But I would never ride that gearing combo anyhow. I can however run almost all the other combinations, and if I am attentive with my shifting (I almost always am), I shouldn't have a problem. I know, not ideal, but usable, at least for now. Best option though is a Med cage fore sure. BTW anyone know how much chainstay growth I would see on an ASR 5? The single pivots are considerably less than the VPP bikes, right?

I know when reading the SRAM 2013 compatibility guide that it says to run a long cage with all of the 2x10 combos with an 11-36 cassette. That to be within spec you would have to use an 11-32 and 2x10. I think the main issue is the max tooth difference. I know with most 2x10's that a 14 tooth difference in the front and a 25 tooth difference in the rear leaves the total difference of 39T larger than what SRAM has said in the past was "OK". The thing I don't understand is if you look at most of TREK and Specialized bikes, they are all spec'd with a drivetrain having a 39T difference. Not sure why they would go against SRAM and build these bikes with parts that are wrong?

I run a 24/38 crank, 11-36 cassette, SRAM X9 medium cage derailleur on my Specialized Epic (also full suspension). You have to size your chain considering chain-stay growth during the compression of your rear shock, and your derailleur needs to take up this extra chain which effectively reduces its capacity. On my bike, the medium cage derailleur cannot maintain adequate chain tension on the small-small gear combinations. You shouldn't be using the small-small combinations anyway, but it may be a consideration for you that some of your gear combinations may be unusable. The long-cage will have enough capacity for all combinations. FWIW, I've put 4500 miles on my medium cage and it hasn't ever caused a problem aside from a few times when I forgot I was in the small chainring and upshifted into small-small.